Former New York governor George Pataki said Tuesday that he’s ending his bid for the 2016 Republican presidential nomination, with just over a month to go before the first nominating contests begin.

In this Dec. 15, 2015, file photo, George Pataki makes a point during the CNN Republican presidential debate at the Venetian Hotel & Casino in Las Vegas.(AP)

George Pataki, New York Governor at the time of the 9/11 attacks, has dropped out of the Republican race for the White House, as frontrunner Donald Trump moves to consolidate his lead.

Trump announced Tuesday he would now be spending $2 million a week on his campaign after, according to him, not spending anything at all so far, while others splurged.

He has also proceeded to target Democratic frontrunner Hillary Clinton more sharply than ever before, targeting her husband — former president Bill Clinton, a one-time friend.

Pataki had run a lacklustre campaign that never took off, and was largely said to have overstayed his welcome, when others with relatively better prospects had exited.

Bobby Jindal, for instance, had consistently polled better than Pataki but he dropped out some weeks ago. Senator Lindsey Graham, who made more headlines, also left.

Pataki became on Tuesday the fourth Republican to give up, after Wisconsin Governor Scott Walker, a favourite of the party’s extreme right before he crashed in polls, Jindal and Graham.

The field is expected to get thinner in coming days, and any of these three are expected to be next — Rick Santorum, Mike Huckabee and Jim Gilmore, the invisible 12th.

Democrats have had their share of drop-outs too — former senators Jim Webb and Lincoln Chafee. There are only three in the race now — Clinton, Bernie Sanders and Martin O’Malley.

Both sides are now focussed on Iowa state, which kicks off the presidential race with a caucus on February 1 — selecting candidates at party meetings through show of hands.

New Hampshire is next which, unlike Iowa’s caucus, holds a primary, a state-wide polling of party members (some states allow independents and rival party members to vote too). Senator Ted Cruz has led in Iowa polls and is expected to take the state with a better ground game there than any of his rivals. Trump, on the other hand, is set to take New Hampshire.

Trump leads in all national poll though, and by an impressive margin — 39% to 18% polled by Cruz, who is in second place, having recently dislodged Ben Carson.